Update .gitignore

Update .gitignore to ignore unecessary files
during a commit.

Partial-Implements blueprint hacking-compliance
Change-Id: I13eca5c8fccd315ec2dc0eb7ec725fa8cc51168d
Add test from oslo-incubator

Sync openstack/common/test to be part of
the project.
Also removes current tests that does not really
relevant

Change-Id: Ia0a2cb20b6c2165cd11faafd7bcaaec3119b8012
Partial-Implements blueprint hacking-compliance